TUESDAY, July 3 (HealthDay News) -- Students with visible disabilities and those receiving special education services for behavioral problems are at greater risk of being bullied and of bullying others, according to a new study.

These children also are more likely to engage in antisocial behavior and have disciplinary problems at school, the researchers found.

The findings reveal the complex nature of bullying, the study authors pointed out in the report, which was published June 27 in the Journal of School Psychology.

"These results paint a fairly bleak picture for students with disabilities in terms of bullying, victimization and disciplinary actions," lead author Susan Swearer, professor of school psychology at the University of Nebraska-Lincoln, said in a university news release. "Sadly, these are the students who most need to display pro-social behavior and receive support from their peers."

The study included more than 800 special-ed and general-ed students between the ages of 9 and 16 from nine different schools. The investigators found that 38 percent of the students admitted to bullying other students and 67 percent said they had been the victims of bullies.

Not only were special-ed students at greater risk for being bullied or bullying others, students with visible or more obvious disabilities, such as language or hearing impairments or mild mental handicaps, were victimized most often. They also reported the highest levels of bullying.

On the other hand, the study authors found that students with non-observable disabilities, such as a learning disability, were not affected as much by bullying and reported similar levels of bullying as students without disabilities.

"The observable nature of the disability makes it easy to identify those students as individuals with disabilities, which may place them at greater risk for being the easy target of bullying," Swearer said in the news release. "Also, being frustrated with the experience of victimization, those students might engage in bullying behavior as a form of revenge."

There were no significant differences in bullying between boys and girls, the findings showed. General-ed students in fifth grade were victimized more often than students in grades six through nine. For students in special-ed, however, there was no difference in bullying by grade level.

Anti-bullying interventions should focus on students' pro-social skills, the study authors concluded. Those in general education could serve as pro-social role models for students with disabilities, they suggested. In addition, students with visible disabilities should be better integrated into general-education classes, which may prevent them from being bullied.

"Programming should be consistently implemented across general and special education, should occur in each grade, and should be part of an inclusive curriculum," the authors noted. "A culture of respect, tolerance and acceptance is our only hope for reducing bullying among all school-aged youth."